Conventionally, there are puffer type gas circuit breakers that are arranged in electric-supply stations, such as substations and switching stations, and extinguish an arc generated between contacts by spraying an insulating gas. An example of this type of gas circuit breaker is disclosed in Patent Literature 1 in which a gas circuit breaker includes, in a container filled with an insulating gas, a thermal puffer chamber, which is formed on the periphery of a movable-side contact (hereinafter, referred to also as a movable arcing contact) among arcing contacts, and mechanical puffer chambers formed adjacent to the thermal puffer chamber in a radial direction.